Ok where do I start first the problem as questioned was does high temp effect or damage the board, yes how? by slow degration over time and temp extreams. the second remark put out was that most PCB people do not know how close we come in damaging the plating in the holes and vias with large temp extreams such as soldering. First the T/G is so missused its is a wide imaginary point at which the epoxy starts to become soft and increases its expansion rate/temp noticably. this expansion force has enough power to lift pads and crack copper in the holes. The T/G has nothing to do with a max operational temp or a max usable temp, it is way above were you want to run a board at.Some materials such as Kapton have no noticalbe T/G. The copper in the hole has a lot to do with how many cycles of soldering you get before the via cracks. The ductility of the copper does effect it, as does its thickness. if you are just below 1 oz and the board is a 4 layer mult .125 thick you may not even see 3 cycles before the vias crack. The thickness and build also play a effect in the cycles. Can you improve it? yes as I stated I found that a little bit more copper realy helps the situation doubling or even tripling the numbers, this doubling takes you out of the scary area of 3-4 cycles which is not uncommon today with mixed components. The statement was put forth that you cant plate 3 oz of copper and have 10:1 ratios well not so . Where do you think the 1 oz copper came from we so dearly hang on to from the 60's when the only copper we could buy was 1 and 2 oz , it worked so we used it, To plate more copper in the holes lets say 2 oz is easy start with 1/4 oz and use thicker dry film ( you will be amased how accrate it can resolve) and drill ever so slightly over and plate 2 oz the board will now be out of the danger zone . But I have found many people have there head stuck firmly in the "cant do that" arena of life. --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------